[csswg-drafts] [css-overflow] Interaction between line-clamp fully displacing lines and line-height quirks (#13708)

andreubotella has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-overflow] Interaction between line-clamp fully displacing lines and line-height quirks ==
The block overflow ellipsis generated by `block-ellipsis` (one of the longhands for `line-clamp`) can fully displace a line box's entire contents, so the line would only contain that ellipsis. While the ellipsis behaves as if it had `line-height: 0`, when it fully displaces a line, it is considered to contain a "strut", so the line doesn't end up having a height of zero (unless the block container also had `line-height: 0`).

However, in quirks mode, the ["blocks ignore line-height quirk"](https://quirks.spec.whatwg.org/#the-blocks-ignore-line-height-quirk) has the effect of removing the strut corresponding to the [root inline box](https://drafts.csswg.org/css-inline-3/#root-inline-box), and the ["line height calculation quirk"](https://quirks.spec.whatwg.org/#the-line-height-calculation-quirk) has the effect of removing struts from any other inline boxes (except that line-left and line-right paddings and borders behave as non-removed struts).

These quirks together have the effect that the height of a line box is not floored by the `line-height` of any inline box, including the root inline box, unless that inline has glyphs.

Given that, how should those quirks interact with the block overflow ellipsis? Since it explicitly behaves like an inline with `line-height: 0`, maybe these quirks should prevent that strut. Otherwise we'd have an ellipsis which would otherwise not contribute to a line box's layout bounds, contribute to them if it's the only thing in the line.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13708 using your GitHub account


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Received on Tuesday, 24 March 2026 10:50:08 UTC